The present invention relates generally to an article transfer apparatus, and more particularly to an apparatus for simultaneously transferring a plurality of articles from one conveyor to another. Still more specifically, the invention relates to an apparatus for simultaneously transferring a plurality of articles from one position in which they travel on a first conveyor in a first direction to another position in which they travel on a second conveyor at lower speed in a second direction transversely of the first direction.
In many instances it is necessary to transfer a number of articles simultaneously from one conveyor to another conveyor moving at a different speed and in a different direction from the first conveyor. This is true, for instance, in the case of articles which are made of glass or similar material which can be readily damaged unless handled gently. The necessity for such transfer occurs, for instance, where a large number of glass objects moves along a conveyor from one step in the manufacturing process to another, and requires to be transferred from the first conveyor to a second conveyor which moves at a different speed and in a different direction. Various expedients are employed for effecting this transfer, including manual transfer, transfer by means of deflecting plates, and other possibilities.
It is also known to provide various mechanized transfer devices, but none of these have been found entirely satisfactory. The problem of transfer is particularly bothersome when the glass objects move to the transfer point at one speed and must be transferred to a surface moving at a substantially different speed. The problem is aggravated if glass bottles are involved, especially tall or moderately tall bottles, because bottles are quite unstable which complicates the problem of transferring them without having them fall over or become otherwise disarranged, with a consequent disruption in the orderly flow of bottles and the likelihood that breakage or other damage such as scalding might occur.
The problem is typically encountered in instances where bottles are carried along a relatively narrow conveyor in a single row, for instance arriving from a bottle forming machine, and must then be transferred to a wide conveyor on which it is necessary to arrange the bottles in ranks extending transversely of the elongation of the wide conveyor, and in a considerable number of bottles per rank. It is obvious that the second conveyor can move at only a much slower speed than the single-row conveyor which brings the bottles to the transfer point, and that the transfer under these circumstances will present considerable problems.
Attempts have been made in the prior art to overcome some of these problems, for instance by providing a pusher bar which is pivoted to two cranks which are of identical length, directly driven and which move at constant angular speed. In this case the problem has been encountered that the pusher bar impacts the articles -- throughout the description reference will be made to bottles for the sake of convenient explanation -- at an undesirably high speed, leading to a displacement of the bottles from their relative positions so that they will not be properly located when they reach the slower travelling second conveyor.
Another attempt has been made in U.S. Pat. No. 2,601,914which describes a transfer mechanism in which an elongated push bar is actuated by combined rotary and oscillatory components which shift the push bar laterally and longitudinally as it transfers the bottles from the first conveyor to the second conveyor. However, by the nature of this construction the push bar -- and hence the bottles being pushed by it -- is subjected to varying acceleration during each operating cycle, and in addition at the moment the push bar disengages from the bottles which it has transferred, it moves with maximum speed in the direction of travel of the first conveyor. This makes it impossible to position the bottles precisely on the second conveyor in the desired manner.
U.S. Pat. No. 2,217,982 discloses a receptacle transfer mechanism having a pusher bar that is pivoted to two pivot arms of identical length. The opposite end of each of the pivot arms is in turn pivoted to a continuously turning crank pin. Each of the arms is provided with a longitudinally extending slot which receives a stationary pivot. In this construction the pusher bar will have a component of speed in the direction of movement of the first conveyor which is approximately zero at the moment at which it engages a group of articles that are to be transferred from the first conveyor to the second conveyor. This is disadvantageous because it is now necessary that essentially the full speed differential between the speed of advancement of the articles on the first conveyor and the substantially stationary pusher bar must be compensated by friction between the latter and the articles. From the moment of contact until the moment at which the pusher bar disengages the articles after they have been transferred to the second conveyor, the component of speed of the pusher bar in the direction of advancement of the first conveyor increases until it reaches its maximum value at the moment at which the pusher bar disengages the transferred articles. This means that here also the same disadvantages obtain as were described before. Moreover, although the component of movement of the pusher bar in the direction of movement of the first conveyor is substantially zero at the time the pusher bar contacts the articles to be transferred, its component of movement in the direction of the second conveyor at the time of contact is already substantial so that the articles are quite abruptly accelerated in the direction towards the second conveyor, which is disadvantageous.
Another apparatus for transferring rows of bottles from a single row relatively fast moving conveyor to a wide slower moving second conveyor is disclosed in U.S. patent No. 3,550,789. In this construction a pair of elongated gripping bars is provided which simultaneously grip the tops of the row of bottles from the fast moving conveyor and then swing accurately on parallel arms to the slower moving conveyor where they release the bottles so that the same can form a rank on the second conveyor. The bars are caused to swing tangentially to the row of bottles which is to be picked up, and at the point of tangent the speed of the bars is synchronized with the speed of the feeding conveyor so that the bottles are gripped by the bars. The construction disclosed in this patent is quite complicated and therefore expensive. Moreover, although this apparatus is certainly operable in the desired manner, its very complexity will necessarily make it susceptible to breakdown and similar problems.
Other attempts at providing mechanical apparatus for the same purpose are also known from the prior art, but none of these devices are fully satisfactory either.